Howdy, IMRS,
Just tried some empirical research on popping tanks/coils/juices. In other words, I looked at the tanks before tootle puffing. Learned a thing or three. Juice color is not, in my 6 tank sample, correlated with popping. Nor is mod charge level or wattage. Prelim conclusion? It may be the juice, itself. The two that are popping have some strong flavors. Could it be a highly flammable ingredient in the flavoring?
Take all this with a grain of salt; what I've done suffers from a multitude of research design flaws, is not peer reviewed, and may not be available in your state. Just a HAG for discussion.