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Is there any evolutionary reason behind Kryptonians having x-ray vision and the ability to shoot lasers from their eyes? In an answer to the question How does superman fly? , it is stated that

Lex Luthor once theorized that Superman had to stem from a gigantic
planet with enormous gravity, where his species had developed natural
anti-gravity organs to be able to function; on Earth, this would allow
him to control his own gravimetric field in order to fly.

Are there any such evolutionary reason behind Kryptonians having the ability asked in the question?

Remember that these abilities are not unique to the humanoid kryptonians but ALL kryptonians. An obvious example would be Krypto the Wonder Dog. I don't know that we have ever seen the power of kryptonians plant life but all of the higher life forms we have seen on the planet become extra-powerful under a yellow sun. This argues for the power being developed by a common ancestor far, far, far back. Perhaps even back when Krypton had a yellow sun, it was developed as both a detection mechanism (the ability to see predator and prey through anything) and a self defense mechanism. As Krypton went red, those abilities diminished, but by that point life had already scattered and adapted to new niches. In addition, Kryptonians would all have been defended from that common ancestor and would have inherited both the ability to use the power but also the toughness to resist it (notice how useless laser vision is on Kryptonians?)

But when Kal-El comes to earth, these dormant abilities wake up again. So the most scientific answer I can give is that they had a common ancestor.

If you have the pure scientific view of evolution, then evolution is not guided. Individuals get random mutations. And if a mutation helps this individual to create more offspring, then this "mutation" spreads out and ousts the others without this mutation.

So IF a random mutation creates an individual with x-ray or lasers, it is quite plausible that it would have great advantages and create more offspring.

So the "reason" that this feats are kept in there genetic pool is because it helps surviving better.

For the origin there is no reason. It's random mutation.

So a better question would be, how does a mutation create such things and how is this biologically possible. But I don't think you get scientific answers for this.

The Why of Laser Eyes

Between 80 and 90 percent of undersea life has some form of bioluminescence according to Edith Widder's TED Talk, "Glowing Life in an Underwater World" which means that as far as life on Earth is concerned, the emanation of radiation is predominant. The rule rather than the exception. Life finds the transmission and reception of waves as incredibly valuable, whether sound waves or light waves or other electromagnetic spectrum segments. Butterflies can position themselves globally for their annual migration simply using internal biological clocks and the position of the Sun over the horizon... that one point of EM data translated into a precise satellite-free GPS that fits in the pinhead of a butterfly's neural network.

Focused or targeted waves have even more utility. It's why sound waves became predominate on land and why bioluminescence took over undersea. It adds communication and more to the ability. It is, in fact, possible to create a biological laser. A laser increases transmission distances and intention.

Humanoid creatures have the evolutionary advantage of large scale flexible cooperative coordination. Insects have large scale coordination but are inflexible... they can act only in relatively narrow programmatic parameters. Higher order animals show far more flexibility, but fall apart if attempting large scale coordination... nothing on the order of insects. Humanoids, however, are able to entertain and maintain abstractions (like law, religion, community, etc) through communication and language.

Imagine a species which gains the ability to telecommunicate over line-of-sight through laser light. They would be able to coordinate over greater distances, faster, more complex ideas (than shouting, smoke signals, etc) and evolve greater and faster sophistication sooner with less conflict. Those able to communicate over longer distances, faster, with more intensity and accuracy are selected and the laser vision gets better and better.

The next step and adaptation for humanoids is learning to cook one's food. Instead of being entirely obsessed with the acquisition of one's daily calories, the advent of cooking frees more calories per eating instance, which accordingly frees time to ruminate, invent, innovate, and create a role of intelligence. The advanced communicators already had an evolutionary advantage of coordinating with other groups, warding off competition and predators, and corralling prey in exhausting marathon hunts where herds found themselves cut-off by lightspeed maneuvers until run ragged, captured and eaten by the fledgling Kryptonians.

At one time or another, a Kryptonian decides to flash his eyes at his food and finds that he's stronger for it. Evolution begins to select for more intense, hotter, more powerful eyes for cooking, above and over, what's necessary for communication. Such selection isn't undermined by technology (the advent of fire) because it's still an integral part of their hunting, feeding, community, culture. Soon Kryptonians are self-selecting for laser strength above and beyond what nature would do and it becomes selectively bred to an obscene degree.

Lex's explanation is actually close to the one given by Superman's parents in the 1978 film. His resistance, strength, and ability to jump high (specifically, they explained he would only "seem" to fly) are due Earths's gravity being lower than Krypton. In early stories, he didn't have the ability to fly and only gained "true flight" once writers stopped trying to explain his powers based on Krypton's high gravity.

I guess what I'm getting at is that writers have given him a bunch of arbitrary powers -- flight, eye stuff, Sunny D -- and have sometimes attempted to explain them, but I do not believe that a sufficient explanation has ever been given that is in line with our current understanding of how evolution works.