If it blows out the coolant with no reserve to catch it and allow it to be sucked back in for proper cooling , you can be cavitating with a air pocket this would make air bubbles.
Usually with a head gasket, the bubbles are more with speed and most of the time blow it out of the radiator with the cap off. Get a good reserve tank or try it with a 2 qt. plastic bottle with a hole in where the hose goes into it and about 1" from the bottom.
Luv the smell of NITRO in the morning.