I don’t exactly remember whether it was a movie or TV episode. All I remember was watching it on a TV channel around at least 10 years ago. It was in color and had aliens in it. I apparently hopped on the channel when it was towards the ending so I do not have a complete picture of the plot but remember the scene quite vividly.
Female alien that can shoot some sort of a blue ray at people. People shooting at her, but the bullets have no effect. A person had one more charge left in this plasma/ray gun and disintegrated the alien…but she was able to reform herself again. The female alien kept saying something like “you killed my husband.” In the end, the alien dies after being kicked into a pool of clear liquid which can either be acid or nitrogen. All I remember was the alien turning redder as smoke filled the room…kinda like being cooked alive.