My laptop starts making a noise like teakettle with boiling water. Why??

Sounds to me as though either your drive or your fan is about to go out. They're the only real moving parts in a computer.

I'd STRONGLY suggest shutting the machine down until you can get a new fan; if the computer gets too hot, the processor will be toast in very short order.

Drives can be replaced; if you slag your motherboard or fry your processor, your computer is effectively gone.