A YouTuber put slime into a vacuum chamber to see what would happen and recorded the whole thing.
As the vacuum sucks the air out of the chamber, the air that is trapped inside the slime has less external pressure exerted on it meaning the air inside is free to expand.
This is why the slime is taking the shape of the container, as the gas spreads it around the inside of the glass.
You can watch the full video on the PressTube YouTube channel.
Produced by Jasper Pickering. Special thanks to Leon Siciliano.