BBC NEWS | Science/Nature | Antibubbles made in Belgian beer

Take some water in a clear bowl or tank
Fill it to the very brim with dishwashing liquid (water with a few squeezes of washing-up liquid in it)
Keep some of this liquid back in a beaker or jug Very gently pour the liquid from the beaker onto the surface of the bowl
Watch beneath the surface as you pour and vary the speed at which you pour
If you find the right speed, you might see antibubbles form as the stream of water descends beneath the surface
You can now watch these antibubbles move and sink downwards and they will eventually burst.