Why does water bubble when it boils?

Join Africa Melane and Dr Chris for this week's round-up of science questions from the South African Cape, including why we can open the doors of a helicopter but not a passenger plane when it's flying, why water bubbles when it boils, what's the best position for sleeping, why fog rises from a lake surface on a cold day, and why boxers shouldn't blow their noses. Plus news of the world's first cannabis consumption...