I came downstairs yesterday morning to my 3yo dd1 microwaving a large beaker of water. Luckily I got there in time before it had heated and had got it out. I dread to think what could have happened if she had heated the water and spilt it getting it out.
She managed to use a toilet stool (carried downstairs) to reach the microwave.
We now have a high stair gate across the kitchen door!