Solution:
Goto: settings -- apps
Enable system apps
Select "HTMLViewer"
Disable this app.

Check all your installed apps.
I had apps like "Phone" or "Call" or "XXX" which were actually malware.

Go to settings--> apps Enable system apps (right corner) Then scroll to "HTMLViewer" Open it and set to "disable" This app is infected. It was already installed when I bought the phone. I don't have the pop-ups anymore, and no self installing apps with names like "Phone"...