The thing that exploded wasn't the argon or the mercury, but the ballast itself: the electrode fusing mechainsm and the voltage doubler was operated and caused the electrolytic capacitor to explode.
Medved said me in the same post in LG, the following things:
"What cause the fire is not only the failing lamp, but e.g. EOL of the ballast itself and mainly the nonpassive nature of such failure.
And if it is the electronic, what fail (and in such case it is the capacitor and/or power stage), the control part can not do anything with any consequence.
The only option is to ensure, then any failure/damage is contained within the CFL assembly, what mean e.g. proper fusing scheme. But this does not end with adding an overcurrent fuse to the input, you have to ensure it will trigger and disconnect the mains in any case soon enough for the "chain of destruction" to stop within the CFL cover.
And here is the core of the problem: The overcurrent fuse is or missing, or there are other current limitting devices, what lower the current so, the overcurrent fuse does not trip, but dissipate power (and cause overheat and fire)."