The reason the lids are popping off is all down to what is in the tablets.
Although the tablets have Vitamin C in them, obviously, they also have a little bit of acid and a little bit of alkali. This acid and alkali are kept separate in the tablet but when the tablet is put in water they dissolve in to the water and so they mix together. When the acid and alkali mix they make carbon dioxide gas. And it's this carbon dioxide gas that builds the pressure up and up in the canister until eventually the pressure becomes too much for the lid and it pops off - flying through the air.
This experiment should be done OUTSIDE!
Do NOT aim the bazooka at you or anybody else's body, eyes or face.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.