Domestic Geek

I've been disappointed with my bubble lights for many years. The ones I had from my mother have slowly burned out or broke, so I finally bought some replacements about five years ago. They never bubbled, though. Kind of misses the point of being bubble lights. Anyway, I was googling how they work because I'm a nerd like that (and still don't know yet), but did find a tip for getting them to bubble. The site said to turn the bulbs upside down (while they're on) for 15 minutes or so and they would bubble again when uprighted. I didn't believe it, but gave it a try anyway and sure enough...it worked! Yay!!!!

Now, if someone would please explain what is in there that makes them bubble, I'll be good to go.