Microwaving hard-boiled eggs is extremely dangerous.
Leafy green vegetables like spinach and kale contain nitrates that can convert into harmful compounds when reheated in the microwave.
Microwaving chicken or processed meats can lead to uneven heating, leaving some parts undercooked while others become overcooked.
Microwaving rice that has been left at room temperature can be unsafe.
Chili peppers should never be microwaved because they release capsaicin vapors when heated.