Typically it goes as follows; you’re using your laptop and everything is fine for about 10 minutes when all of a sudden it switches off. No error message, no warning and no time to save your work. You check your battery and it’s fully charged and the same thing happens even when connected to the mains, so not likely a power issue

This is a problem that rears its head much more often in the summer months and is all down to the limited airflow available within the casing of a laptop, as compared to a desktop pc. Modern processor get very hot under load and this is usually dealt with by the heat-sink and fan assembly in the laptop transferring the heat away from the processor and blowing it out of the side vents.
As the weather warms up, the difference in temperature between the “cool” air being drawn in and the hot surface of the heat sink decreases and cooling becomes less effective.

This alone should not cause the laptop to trigger a thermal shutdown but couple this with a thin layer of dust on the heat-sink and it can be enough to tip the balance.
I’ve seen high-end gaming laptops experience this problem with only a tiny (almost imperceivable) amount of dust in the heat-sink assembly but sure enough, cleaning this out resolves the problem.
Even if your laptop is relatively new and has been kept quite clean, it’s quite possible for a layer of dust to build thick enough to make it overheat in the summer months

Cleaning is usually straightforward as most laptops will have some covers underneath that allow access to the heat-sink (it will look like a shiny metal radiator). By opening these covers and locating the heat-sink and then removing and cleaning with a paintbrush, a seemingly broken laptop can quickly be returned to a working state.

If your laptop has no such access cover I suggest getting a can of cleaning air and directing it into the air vents. This isn’t as effective as removing the heat-sink assembly but should still make a difference and hopefully prevent any more shutdowns for a while.
While it might seem like a good idea to vacuum the air vent, this isn’t advisable as the air tends to ionise and can cause static to build up. Static is the enemy of any precision electronic device and should be avoided wherever possible