Depends on how hot. Resisters that overheat are overloaded. Potentiometers are not meant to be high power devices. If enough power is being dissipated by a potentiometer that it is getting "really hot" than the circuit is probably malfunctioning or it is poorly designed.
How many ohm is your potentiometer? If you are designing a 5v power supply a potentiometer to divide the voltage isn't going to work for you. If you tell me what you are trying to do I can give you a suggestion how to approach your problem.
Yeah resistors get hot 'cause the energy they're restricting from passing through is expelled in other ways - heat. That's why phone chargers get hot, they're basically giant resistors. :)
It's just like 12v in and i have it set letting about 5v out