Passive "Explosive Impact"

I don't think the passive triggers at all

I understand that 5% is a small chance and also I might just be missing the effect when it goes off, however I am pretty confident that the passive is not doing anything.

I've been consistently using Flame Wall + Fireball to ignite enemies and I haven't seen one time the effect happening (this is assuming it's the same visual and sound effect as the Detonate Dead skill or the support gem Fiery Death)