The thermostat is usually the first part to blame.To check it,drive the vehicle til the gauge reaches its normal position,then it should begin goin back down as soon as the thermostat opens.If the gauge doesn't go down or continues going up,turn the heat on full and place your hand over the vent to see what temp is felt.If cold or luke warm air is felt(instead of hot air)the thermostat is sticking closed and needs replacement.If you don't wanna drive the vehicle and prefer letting it idle til it warms up to operating temp,make sure the cooling fan comes on when the gauge reaches 190-210°.If the engine overheats when idling but seems to be fine when the vehicle is in motion,the cooling fan is most likely not working and causing the overheating situation.If it overheats when idling and when in motion,the fan is usually working and not the cause.When moving airflow through the radiator cools the antifreeze down then it swaps places with the hot coolant in the engine.

Remove the thermostat you have to replace it you can it leave it without thermostat it won't damage it.... The best way to cool it off when it boils turn on your hot air a/c max and open windows that will help you get to your location safe

Could be several things but the most likely three are---the radiator fan is not working, or your thermostat is stuck closed, or your water pump is not working.

..or you simply blew the head gasket