Re: "suddenly become vapor..."
No, I'm not confusing MDMA and the street term; Ecstasy. While I'd agree adulterants were commonplace (PMMA being one of the commonly used dangerous substitutes that has caused deaths in the past - see Eric Prydz @ Alexandra Palace event 2011), the recent sweeties have been flagged as containing only MDMA but at a dosages above 260 mg - well above those deemed necessary (Alexander Shulgin stated 125 mg is the optimal dose for MDMA).
It frankly re-enforces the case for legalizing drugs, but that's another issue.