A bad thermostat could indeed cause the coolant to boil if the thermostat is stuck in the closed position and not opening up and allowing the coolant to flow properly throughout the engine.
A thermostat that is stuck open will not overheat the engine or cause the coolant to boil but a closed thermostat that is bad and stuck closed could cause the boiling of the coolant and cause overheating.
So if your car is overheating it could be a stuck closed thermostat or even a bad radiator cap or clogged radiator.
I would also check your radiator cap because the radiator cap could be bad which is another cause of coolant to boil.
Replace the radiator cap and see if that stops the coolant from boiling as radiator caps are pretty cheap and easy to replace and they need replaced every now and then anyway.
It's recommended to replace your vehicles radiator caps every 100,000 miles.