I know you did not expressly "advise" it , however sometimes "noobs" read these threads and not always thoroughly so all they see is "boil the rock" and fail to read "I scrubbed them clean first". In any event, there are numerous things in our tanks that we do not want to aerosolize(sp) and yes palys and zoas can be deadly. There are several reports each decade of people getting very sick from boiling rocks. Therefore best practice is just don't do it.
If you mean literal boil, as in boiling water; yes that’s very dangerous. As @SoggyNW mentioned about the toxins; you can also get air trapped in crevices deep in the rocks and as the temp rises, the rock can explode. Please reef safely!!
