Boil water inside a small container with an arduino
Try to find a boiler pot on electricity (I doubt you can heat water to boiling temperature with like 5V (unless you use many amperes).

Use a relais to switch it on with an Arduino.

Use a temperature sensor (0-150 degrees or so) to decide when to switch it off. 

Warning: Get first some electrical knowledge before you start with >200 volts projects since it can be deadly. And boiling water can be devestating for skin and your Arduino.