Bright light in the sky, in the '90s, what could it have been? Sometime in the summer months during the years from 1993 to 1998, my friend and I saw what looked like a gamma-ray burst (or what looked like an artist's impression of it). It looked like a star that got very bright (within a few seconds) and we saw what looked like a line shooting out from the sides of it that spread across our field of vision. All this happened in less than 10 seconds.

I can't confirm when it was any more exactly than that, unfortunately, as we were walking near my friends house at night in the summer, as we did hundreds of times in those years.

According to Wikipedia, the first naked-eye brightness gamma ray burst happened in 2008, so I imagine that's not it. 

What could it have been?
Gamma ray bursts are very rarely bright enough in visible light to be seen with the naked eye. This is why they weren't detected until there was a network of satellites looking for atom bombs. You didn't see a GRB.

If what you saw was Bright, and Fast it was likely to be a bright meteor, sometimes called a fireball. These appear as a very bright, fast-moving "shooting star". They are rare, but not so rare that it would be possible to identify a particular event from the information that you give.

A reflection from a satellite can look like a star that brightens and then fades. The Iridium satellites are well known for this though other satellites can also produce "flares". Iridium flares have been visible since the late 90s.

There are other mundane possibilities, but these would seem to be the most likely. Remember memory is a funny thing. After 20+ years thing that you "remember" might be different.