possibly a bad head gasket
you might need more coolant
No. Excessive pressure will not cause the water to boil off quickley. It will cause the radiaor hose or other components to burst causing loss of coolant. A bad radiator cap can cause high or low pressure; low pressure will cause the coolant to boil at a lower temperature.
Water under pressure has a higher boiling point, if the water is already hot enough to boil it will suddenly erupt when the cap is removed and pressure relieved.
Water in a car radiator does not normally boil. In some old cars, the cooling systems would run at about 220 degrees Fahrenheit. The pressure would be high enough so that the water would boil at 250 degrees. Today, you do not put water in radiators but coolant. It is much more efficient than water for cooling engines.
replace your radiator cap...
Engine coolant temperature is cooled by the radiator, moved by a water pump and controlled by a thermostat. If there are troubles with any of those components the coolant will boil Also if the head gasket goes bad gasses from combustion inside the engine will get into the coolant and cause it to boil.
heat
Can be the thermostat which is cheap to replace, or it might be the head gasket which is expensive.
If the electric cooling fan(s) are not coming on that may be the problem.
Excess pressure is building up in the radiator probably from a blown head gasket and is exiting through the radiator cap and into the overflow bottle.
to get hot
a stuck closed thermostat,a blown head gasket,a cracked head,a faulty water pump,low on coolant,
It's a pressurized system. When it exceeds cap release pressure, it comes out.