'Exploding e-cig cost me 7 teeth, burned my face – and broke my sink'

This person had what's called a mechanical e-cig, or "mech mod". They use no electronics, just a big switch or relay and the sometimes sub-ohm coils used for heating the liquid.

A mech mod works by nearly short circuiting a lithium ion battery. You need to carefully measure and build your coils to provide sufficient resistance and only use it in short bursts. You also need to use a battery (or batteries) capable of delivering the amperage you're asking of it (them). If you don't follow these rules, or if something gets damaged and your device short circuits, you're going to have an unhappy battery in your hands/pocket.

What happens when a lithium ion battery goes nuts? See article.

There have been regulated e-cigs for years with electronic controls both to limit current and time things out if a button gets inadvertently pressed. Those don't blow up.

Mechanical e-cigs are not for normal users. They're for the "cloud chaser" competition types trying to be human fog machines.

You can kind of analogize mechanical e-cigs to nitrous oxide in a car. It's a cheap way to get a lot of power but you have to use it carefully if you don't want to blow things up.