iPhone fire
Lipoly batteries are inherently unstable, that is why they have such a good charge density. There are many ways things can get ugly. If the internal resistance goes up in a cell, routine charging amperage starts to heat the cell. If the charger provides a little too much voltage, the the cell heads towards microwave popcorn appearance, then gas vents explosively. I have some monster lipolys from my airplane hobby, and I keep them in a latched metal box. In the hobbyist world, there have been wrecked model planes loaded into the user's car, and a delayed battery fire torching the car. I try to never charge lipoly batteries unattended, or at least try to imagine how the fire (however unlikely) would behave in the charging location... A few fires out a few million devices is about the best one can hope for.