Hi, and welcome to Android Central. Have you installed any apps recently that might have loaded a virus onto your device? have you tried removing some of the more recent apps you downloaded to see if this resolves the issue?
Have you tried doing a factory reset? It's an extreme method, but one that will work as it will remove everything from your phone and bring it back to factory settings.
Before you do that though, where are you seeing the popups? when you open up the internet app?