cuisine kettle?

my electric, cordless kettle switch on, starts to warm water then the light on the switch goes off and the Warming noise slows then stops, then light on switch goes on and it starts to warm again, the kettle does this several times before reaching a boil at which time the switch turns to the off position. what is going on with the kettle, is it the switch, the element, or the conection between the electric base and the kettle bottom? help