Lava Lamp experiment! Is it a fizzer?
Method: into a small amount of water add food colouring. Add cooking oil to fill the container. Add a soluble asprin (or another substance that fizzes) and watch an amazing lava lamp show begin! (instructions from ABC radio)
Repeat, as desired, later on, when the action finishes and the fluids settle and clear, the oil may be recovered again. Green or blue could look best. Olive oil was used here. Don't use a tightly fitted lid.