I’ve had it happen once (and I rarely ever boil water in there, usually just heat it up), and glass or ceramic are extremely scratch resistant, unlike metal, so no need for a new container. And filtered water tends to work well enough.
So then the recommendation should be 'never boil filtered water in the microwave, and never boil filtered water in a new pot on a stove', not 'never boil water in a microwave'.
Edit: or maybe 'Never boil filtered water in a glass or ceramic container' that makes it clear that the method of heating is irrelevant, it's the condition of the water and container that is important.
I've boiled water in the microwave thousands of times, it's never been superheated. It's does not easily happen in a microwave.
Every time I've seen someone test out this microwave myth, they use distilled water and a new container.
I’ve had it happen once (and I rarely ever boil water in there, usually just heat it up), and glass or ceramic are extremely scratch resistant, unlike metal, so no need for a new container. And filtered water tends to work well enough.
So then the recommendation should be 'never boil filtered water in the microwave, and never boil filtered water in a new pot on a stove', not 'never boil water in a microwave'.
Edit: or maybe 'Never boil filtered water in a glass or ceramic container' that makes it clear that the method of heating is irrelevant, it's the condition of the water and container that is important.