I can’t tell for sure what it was, but jhana might be a possibility. Maybe first jhana? The fireworks thing sound like first jhana to me, although I’m no expert.

I have never ever been stuck in jhanas. If you are under the illusion that you can’t get out of it, for some reason, just do a subtle movement with a finger. I have woken up in jhanas, or at least with jhanic qualities to my mind state (exactly what qualifies as jhana is much debated, so I can’t say anything certain) but that has never been a problem as far as I can see. Pleasurable, sure, but they always end. I think fear might end them effectively if that were to be the case. Then again, if fear arises, the jhana has probably already ended. These states are very temporary.

Thanks for your reply. 

Since then I haven't had that experience  again. I also suspect it to be something like jhana, but it's hard for me to believe that I was able to get a jhana after one month of practice.