When the pressure gets too great, a crack forms, allowing a burst of water to come up to the top, looking similar to a bubble. The crack fills with sand almost instantly and it starts over again.

Make a SPOOKtacular bubbling cauldron at home powered by the magic of science. You may not have a cauldron in your kitchen cupboard, but a bowl or mug will look just as effective. Let Big Manny ...

Who’d have thought that a quick spot of boba tea would also be capable of doubling up as a versatile liquified petrol bomb?