A raisin in a glass of soda water (or champagne) will continuously bounce up and down from the bottom of the glass.
This motion is because of the dissolved CO2 in the champagne. The CO2 bubbles form on the surface of the wrinkly raisin, lifting it up to the top. When the bubble escapes off the water surface, the raisin sinks again. Bubbles form on the raisin because the dissolved gas often needs a nidus to form. The wrinkly raisin provides the perfect imperfect surface for gas bubbles to form.