Why did the warm water bag explode?

Generally, there are salt crystals in hot water bottles. After water is injected, the salt crystals melt and water becomes a salt compound. After the hot water bottle is fully charged, the salt compound will be electrically heated.

Because the electrode may be corroded and rusted when immersed in salt compounds for a long time, the resistance of the thermos bottle will be reduced and the heating power of the thermos bottle will be increased. At this time, if the thermostat and non-self-resetting thermal circuit breaker of the electric thermos bottle fail, the heating temperature of the electrode may exceed 100℃, resulting in the vaporization of salt compounds and further explosion.