Super-heated water droplets are able to navigate mazes on their own, if you build the maze in the right way.
It's caused by something called the Leidenfrost effect - in which a waterdrop does not boil away instantly when hitting a hot surface but instead skits across it, due to insulation provided by the vaporised outer later. If you give the surface the right texture, you can cause it to move in only one direction - and if you heat it, the water appears to navigate a maze on its own.
The Leidenfrost Maze built by Bath's Carmen Cheng and Matthew Guy "to demonstrate the self-propulsion of Leidenfrost droplets at public outreach events and schools".
Take a look, below.