Therefore the electrical energy input is converted to heat energy in the kettle to heat up the water. Some will be lost not all the electrical energy is converted to heat energy within the water.
There will be heat lost to the outside as the temperature of the water increases above room temperature. It takes a long time to boil water when the room is cold or you are outdoors camping in the cold.
In the end the water will boil and the electrical energy will then turn the water to steam, if the kettle does not turn itself off on its own.