For the record, it doesn't occur on my laptop (in Chrome, FF or IE11), nor on my Android devices. There are the targeted ads that appear at the bottom of the page however, not so much pop ups.
I was on my smartphone (not Tapatalk) on Chrome browser. At 1st I thought it was a virus, as it said your phone has been infected with the "four virus" and I couldn't close the page. Then realised that it was another tab that had been opened. So it must have been a scareware ad. And it did.