When a liquid is dropped onto a smooth plate that is heated to a specific temperature well above its boiling point, boiled vapor will get trapped underneath the remainder of the droplet insulating it from the hot plate, allowing it to dance around the plate like oil on a wet surface in what is known as the Leidenfrost effect. Intriguingly, surfaces that are grooved into the shape of a saw blade will cause droplets suspended by the Leidenfrost effect to predictably skitter in the direction of the groove, allowing University of Bath undergraduate students Carmen Cheng and Matthew Guy to build a fascinating maze. [more inside]
Self Propelled Liquid Droplets : When a liquid drop is placed (.mov files) on a surface held at a temperature much higher than the liquid’s boiling point it hovers on its own vapor cushion, without wetting the surface.
The Leidenfrost Effect. It's the reason that water droplets don't instantly evaporate off of a hot plate between 200 and 300 deg C. Another obscure physical phenomenon? Perhaps - except for Jearl Walker, the physicist who uses it for some awesome demonstrations: sticking your hand into molten lead, walking on hot coals and gargling with liquid nitrogen.