If you press as hard as you can against a brick wall until you begin to sweating and breathing hard did you do any work on the wall? explain.

No, as long as nothing moves you aren't doing work, since W=F.s. You have no s, so no W

The radiation of the fire causes the saucepan to heat up. the conduction of the saucepan then to distribute the heat over the saucepan and to give heat to the water. the convection of the water distributing the heat within the water, till all the water is boiling