Sustained elevated heat, increased voltage, etc. It's not magic, it's not unheard of. Research it online.
FYI there is software that is written deliberately to kill PCs by trashing hardware components. Research it online.
It's not unheard of, but it's rare and should not happen (normally). Thermal protection is something all system builders should consider. I'm not talking about the CPUs and other classic bridges on the mb, but also about the chassis design, temperature monitoring inside the chassis and airflow control. I saw a very small number of laptops being overcooked by software, but it eventually should shutdown if something is wrong. Increased voltages are a result of high resource usage, and along with increased voltage, temperatures go up, but up until a certain point, which the system builder decides it's safe. Throttling the components is also something all manufacturers are implementing these days. Some manufacturers unlock settings in the BIOS regarding warning and shutdown temperatures - i consider this extremely dangerous, they should do the research, not us.
I never heard of such a big meltdown before. I saw melted wires and other stuff because the laptops were full of dust and they were overheated constantly - high resource usage (and also because of the faulty design) but all of them were newer ultrabooks. These have a tendency to overheat, everything is so crowded inside the laptop, barely a few micrometers of distance between the components and almost no airflow in the chassis other than the coolers/pipes on top of the CPU and GPU (and all the fancy marketing the manufacturers are presenting won't cool the laptop).
Thing is, might not be the fault of MS. For sure part of the problem, or may i say "the trigger", but eventually the laptop should automatically react to high temperatures. Just my thoughts on the issue.
Update: i had a Sony Vaio ultrabook a few years ago, a beauty, carbon fiber chassis, power, everything. One day it just shut down. It didn't power on for 30 minutes or so. After it eventually did power on, it shut down after another 5 minutes. I took it apart, found the cooler (the plastic parts) melted all over the heat pipes on top of the CPU, like it was on fire or something. Obviously no warranty after 2 and a half years. Couldn't find replacements parts, contacted Sony and everything. So it's now a piece of garbage because of the faulty design.