When you decide to upgrade to a more advanced mod suck as Kanger Subox, Istick etc that are designed for sub ohm vaping. In basic terms sub ohm means you get a whole lot more vapour production. There is just no comparison  if you are currently using an ego, pen style e cigarette. With pen style e cigs the wick is very small and cannot feed the element fast enough to get a very large vapour and because of this are prone to burnt hits, sub ohm coils are far larger and designed to absorb many more times the amount of liquid and thus can keep up with demands of the mod without burnt hits which nobody wants.