above the level? that means its just boiling over some, which is normal and why you have a catch can for coolant.

now if your boiling coolant IN the overflow tank, that could def mean blown headgasket.

you can do a radiator carbon monoxide test. you can get them at car quest for like $10-15. basically you put it on the radiator where the cap would go when the car is completely cool. Then you put this die in that container, start the car and if you have carbon monoxide entering your radiator, the liquid in the container will change colors.