Great piece by Alok Jha for The Guardian:

Water breaks all the rules. Since the 19th century, chemists have developed a robust framework to describe what liquids are and what they can do. Those ideas are almost useless at explaining the weird behaviour of water. Its strangeness underlies what happens every time you drop an ice cube into a drink. Think about it for a moment: in front of you is a solid, floating on its liquid. Solid wax doesn’t float on melted wax; solid butter doesn’t float on melted butter in a hot saucepan; rocks don’t float on lava when it spews out of a volcano.

Via Tools & Toys.