When you hold the lower part of the glass tube the liquid shoots up to the upper portion and seemingly boils. Hold the top section and liquid returns to the lower element.
Try it for yourself, This is a result of Charles' law.
Please note, this is not intended to be used as a toy.
Comes in four assorted colours, so the colour you receive will be one of these - light blue, pink, purple or green.
Approx. 17cm high, 5cm wide (at widest diameter)