I’ll get some stuff together when I get a moment, but if it helps, one of the pop-ups originated from ib.adnxs.com
Edit: Chrome on a Nexus 4
Further Edit: ib.adnxs.com does indeed set a cookie in Chrome – Settings > Content Settings > Website Settings, you may see it in there. Which could be a clue. I haven’t had an ad for a while, but I am going to bin the cookie as a first step.