How does a volcano work?

Volcanic eruptions are always spectacular with their huge flows of incandescent lava and fragments of magma projected several tens of kilometres away into the atmosphere. Still one may wonder what they are caused by. From the pressure cooker to a glass of beer and the honey pot, Sylvie Vergniolle, a volcanologist at the Institut de Physique du Globe de Paris (Paris geophysical institute - IPGP), has put together a small selection of cooking metaphors to help us understand how volcanoes work behind the scenes.