Regulated mods (ones where you set voltage/wattage/temperature) have a really good track record, but there's also that rare one that has a fault, or one that someone has modified or done something stupid with...
Mechanical mods (where you press a button that makes the battery contact and complete a circuit) have a good track record too... IF THEY ARE USED CORRECTLY, and people aren't being stupid... like trying to fire a 0.05 Ohm coil, or using batteries that cannot handle the Amp demands their coil is pulling. Explosions were still uncommon even years ago, before battery technology became better!
Like @Tam said, most problems are with cheap Chinese batteries, knock-off batteries, damaged batteries, or where someone pops a battery into their pocket or purse (unprotected) and loose metal manages to make contact between the positive and negative posts, creating a run-away discharge/venting.
There's no reason to panic... your mod is 99.9999% safe if used correctly AND you are using a good, reputable battery of the correct Amperage specification for your coil needs. Stick with Samsung, LG, Sony, etc. batteries, and make sure they are at least 20A... and you should be fine for all your vaping needs.