I thought it was from Waze. So I took it off and that didn't help and advertising web screens were popping up everytime I change screens and it was extremely annoying. So I started removing a whole bunch of programs that I saved because I drove up to New York from Florida. So some of them were hotel booking apps and some were TV to go apps. But I don't think any of them had anything to do with this. I don't remember the two apps that I took off after that that I think probably caused it and is there any way to find out what apps you removed. One of them had a name like T-Fal or T-Val and it had an icon which looks something like a sword shown vertically on a dark blue cloudy background. The other program had multiple colors like vertical panels of colors and I think that had a name something like Fillin. I should have taken a screenshot of that page cuz they were all on my last page but I didn't But I do think it's one of those two apps. I think since I took off all those programs I haven't had it happen again. But if it does I will let you know.
If you installed the apps from Google Play, you might try opening the Google Play App then:
-Go To:
Manage Apps & Device
-Go To:
Manage
Change the drop down from 'installed' to 'not installed'. The apps you deleted might still be listed there.
I have old apps listed there that go years back.
Glad you were able to stop the ads!