Sounds definitely like a leaking battery. Very odd a brand new battery would do that. The only ones I have seen were very old NiCad or 1st generation NiMh batteries from the early 2000s. I would never use them once they developed the white power residue. Hopefully this is an isolated issue and not a bad batch of these new batteries which until now were regarded very highly.
As far as the charger I would suspect it is shorting out to cause the popping. Hopefully it is not like the early revision v32 LaCrosse chargers that were infamous for getting stuck in a loop where the mains would send full current and cause the charger and batteries to melt or worse in well documented threads over at Candlepowerforum. I personally have had a LaCrosse BC900 exhibit the same problem where the display was frozen but the charger was running away at full bore and achieving meltdown once I smelled an electrical smell and the batteries wrappers were shrivelled up. Good thing I was there or else the house could have burned down. Hope this also is an isolated issue as nothing worse than a charger needing to be supervised and a half baked user not sure if what is happening is real or hallucination. Bad combination and gladly this has not been an issue prior to this as far as I know.
As far as the charger I would suspect it is shorting out to cause the popping. Hopefully it is not like the early revision v32 LaCrosse chargers that were infamous for getting stuck in a loop where the mains would send full current and cause the charger and batteries to melt or worse in well documented threads over at Candlepowerforum. I personally have had a LaCrosse BC900 exhibit the same problem where the display was frozen but the charger was running away at full bore and achieving meltdown once I smelled an electrical smell and the batteries wrappers were shrivelled up. Good thing I was there or else the house could have burned down. Hope this also is an isolated issue as nothing worse than a charger needing to be supervised and a half baked user not sure if what is happening is real or hallucination. Bad combination and gladly this has not been an issue prior to this as far as I know.