You had the initial bubbling over due to all the air in the cooling system. As air expands much faster due to heat it will escape.
One way you can verify that the coolant is full. Is to start the engine with the reservoir cap open. As the coolant circulates through the engine the level can go down. If it does not go down, you can squeeze the radiator hose a few times to purge the system of any trapped air.
It is best to do it when the engine is cool that way the hose is not burning hot.
If the coolant level stays at a sable level fill up to the desired mark.
That should take care of this.
Let me know of any questions.
Friday, November 19th, 2021 AT 6:45 PM