I just reinstalled my operative system, and with that my Firefox settings got reset. I know there is an entry in about:config to prevent ads from opening new tabs and pop ups without authorization, even from legit websites like the login pop-up windows when doing a sign in in Google, in those cases to allow the windows it's needed to click on the lock icon next to the URL bar and allow it from there. The problem is that I don't remember the name of that setting and I have spend an hour looking for it on Google.