But even though microwaves are incredibly helpful, they’re not the perfect solution for heating everything. In fact, microwaving certain foods can actually be dangerous or harmful to your health. Some foods change in a way that makes them unsafe to eat, while others can create a messy or even explosive situation in your kitchen.

Let’s look at five foods you should never microwave and why.

Hard-boiled eggs are a surprising food you should never microwave. When you try to reheat a hard-boiled egg in its shell, pressure builds up inside the egg. The steam has nowhere to escape, and the egg can explode, making a huge mess or even burning you if it bursts after you take it out of the microwave. Even if you’ve already peeled the egg, it can still pop. It’s best to heat hard-boiled eggs on the stove or eat them cold to avoid any risk.

Many parents use the microwave to warm up bottles of milk for their babies, but microwaving breast milk is a bad idea. The uneven heating from the microwave can create hot spots in the milk, which can burn your baby’s mouth. Also, microwaving breast milk can break down some of the important nutrients and antibodies that are good for your baby’s health. Instead, warm up breast milk by placing the bottle in a bowl of warm water or using a bottle warmer.

Putting frozen fruits in the microwave may seem like a quick way to thaw them, but it can change the texture and taste of the fruit. Even worse, microwaving frozen fruits can destroy the healthy antioxidants and vitamins they contain. Some fruits, like strawberries and blueberries, can also get mushy and unappealing when microwaved. It’s better to let frozen fruits thaw naturally in the fridge or at room temperature for the best results.

Leftover rice might be one of the most common foods people microwave, but it can be unsafe if not handled correctly. Rice contains spores of a bacteria called Bacillus cereus, which can survive the cooking process. If rice is left out at room temperature for too long and then reheated in the microwave, those bacteria can multiply and cause food poisoning. To be safe, store cooked rice in the fridge as soon as it cools and heat it thoroughly on the stove or in the oven.

Microwaving chilli peppers is a recipe for a very painful experience. When chilli peppers are heated, they release capsaicin, the compound that makes them spicy. Microwaving intensifies the release of this chemical into the air. If you open the microwave door after heating chilli peppers, you could accidentally inhale the fumes, causing burning in your eyes and throat. It’s best to heat chilli peppers on the stove, where you can control the cooking process more easily.