What you need:
Empty effervescent tablet tube
How the experiment works:
( Caution: The experiment is best carried out outside. If you do so, you won't need a glass)
1. Fill the empty container with some water (approx. 2 cm high).
2. Add an effervescent tablet and close the container quickly with the cap.
3. Shake the container (not too long!).
4. Place the container upside down (the cap is down) inside the glass and quickly take a few steps back.
What did you observe?
As soon as the water and the effervescent tablet are combined, carbon dioxide is produced. At some point, there is so much gas inside the container that the lid cannot withstand the pressure, causing the container to fly up into the air.