I was scrolling the clock app and saw a woman test cooking pasta in a thermos. She said it didn't work because she couldn't open the thermos after the cooking time. I think possibly she filled it too high, and it pressurized, creating a tight seal like a jar would. I had to try it for myself!
This is a re-upload because the video quality was really bad the first time. Hopefully, this fixes it. If not, thank you for watching anyway!