Take one cup of fizzy pop, a handful of raisins and watch the fruit have some fun! The raisins rise and sink though the liquid for quite some time - at least an hour and a half.
How do they do that?
Fizzy pop contains bubbles of carbon dioxide. Raisins are wrinkly, crinkly little things which the bubbles can get stuck in and on. When there are enough bubbles stuck on the surface of the raisin, the raisin becomes lighter than the surrounding liquid so the raisin rises to the surface of the liquid. Here, the bubbles pop and escape into the atmosphere. Suddenly, the raisin becomes too heavy to float on the surface of the liquid and so it falls to the bottom of the cup again. This process repeats until the liquid no longer has any carbon dioxide bubbles dissolved in it.
This process is called carbonation.
When the pop is flat, the raisins stop raving!