How does the electric kettle work?

Electricity travels through the element inside the kettle, but resistance to the flow of electricity causes heat. The heat is then conducted into the water. When the water reaches boiling point, the steam heats up a 'Bimetallic Strip' which is made up of two different strips of metal, which bends because one of the metals expands faster than the other. This breaks the circuit, and the electricity doesn't get through the element until the bimetallic strip has cooled down.