According this video when the coolant squirts, while the cap is of and the engine is running, this is an indication for a leaking head gasket.
I have tried this method on my car and have somewhat different results. Bubbles are forming, but there is no squirting. Is this a clear cut case of a faulty head gasket, or are the bubbles not enough?
I also have other symptoms, like oily coolant, losing coolant.
This is what it looks like on my car: video