No I am not making this up, at a point in the 80's I had a DC comic (rather thick for a comic book), one of the stories in it featured an old, grey-haired woman who had a Green Lantern ring and the powers that come with it. The villains of the story had her trapped in a yellow bubble, which she escaped from by popping it with a needle she created with her ring. If it helps with identification, the comic also had a rather bleak Superman story where (I think) the Man of Steel imagines a nuclear war he was unable to prevent.
You're almost certainly thinking of KT21.
She was an alien member of the Green Lantern Corps, hailing from the planet Jerome, and made her first appearance in Green Lantern Vol. 2 #187 (April 1985), which contains a scene very similar to the one you described.
As you stated, she was trapped in a yellow sphere, and escaped not by projecting a needle construct with her Green Power Ring (since Green Power Rings couldn't directly affect anything yellow back in the '80s), but rather by inflating a bubble of red plastiglass within the yellow sphere, and then striking it with a hammer construct hard enough to shatter both.
The story was titled "Forever Blowing Bubbles!".
Incidentally, the Superman story you described was likely from Superman Vol. 1 #408. It did help with the search, as I managed to ID the Superman issue first, and then used the publication date of that issue (June 1985) as a guide to when the Green Lantern story was likely to have been published.