What is happening here?

https://www.youtube.com/shorts/GwVEXs81gHs
https://www.youtube.com/shorts/7srGHaLRGgs

I had an coolant leak probably from the temperature sensor. (13621433077).
I changed the sensor and the hose (17127509963).

Now this happens. It seems like pressure and air build up. First time I tigthen the expansion tank cap. Then the expansion tank broke.
It starts to happen when the engine gets hot