Yes the electrolyte will vaporize if the battery is overcharged.
Add distilled water to the battery cells. Get the water just so each cell in underwater. And then find out why it is dry. Could be the voltage regulator is defective and the battery is being overcharged.
Dirty battery connections created a spark when cranking the starter on a possibly overcharged/overheated battery causing an explosion.
The reason for the battery to loose water is due to the heat, in which the water will evaporate... that is why when you refill water they say to only use distilled water, as the acid is now much more concentrated. A battery that is being overcharged will also loose the fluid.
charge controller
Minor bubbling is normal when battery is charging. Excessive may be due to the battery being overcharged--perhaps a bad voltage regulator.
Any lead-acid battery system when overcharged will produce hydrogen gas.
If your car battery smells like "rotten eggs" then your battery is producing excessive hydrogen and is probably not safe. Please check you cars' charging system and make certain that the battery is not being overcharged. The battery can possibly explode.
Yes, if the charger does not automatically shut down when the battery is fully charged.
It's possible, if the batter is severly overcharged, but this rarely happens nowadays. Batteries are designed to prevent this.
Battery will either be overcharged and burn out numerous electrical components or battery will be undercharged and eventually won't have enough voltage to operate vehicle
add water and charge the battery
Car batteries are filled with sulfuric acid, not water. The battery fluids get "topped up" with distilled water if they get low.