When eggs "explode" or crack while boiling, it is typically due to the buildup of steam pressure inside the egg. This can happen for a couple of reasons:
Air Pocket: Eggs have a small air pocket between the inner and outer membranes at the wide end of the egg. As the egg is heated, the liquid inside turns into steam, and pressure can build up if the steam has no way to escape. If the air pocket is trapped, it can cause the egg to crack or even "explode."
Rapid Temperature Change: Placing cold eggs directly into boiling water can cause sudden expansion due to the rapid increase in temperature. This expansion can create cracks in the eggshell, especially if the egg is too cold or the water is boiling vigorously.
To reduce the chances of eggs exploding while boiling, follow these tips:
Start with room temperature eggs: Allow the eggs to come to room temperature before boiling them. This can help reduce the temperature shock and minimize the risk of cracking.
Use a gentle boil: Bring the water to a gentle boil rather than a rolling, vigorous boil. A more moderate boil reduces the risk of the eggs knocking into each other or the sides of the pot, which can cause cracking.
Add a pinch of salt or vinegar: Adding a pinch of salt or a small amount of vinegar to the boiling water may help coagulate any egg white that seeps out of a cracked egg, reducing the mess if an egg does crack.
Use a spoon to gently lower eggs: When placing eggs into the boiling water, use a spoon to lower them in gently, rather than dropping them from a height.
Poke a small hole: Some people suggest poking a small hole in the rounded end of the egg with a pin before boiling to release pressure more easily. However, opinions on this method vary, and it might not always prevent cracking.
If an egg does crack while boiling, it's still safe to eat as long as it's cooked through. However, it might not look as visually appealing due to the white leaking out from the cracked shell. If you want perfectly intact boiled eggs for presentation purposes, it's best to be cautious and follow the tips mentioned above to reduce the likelihood of explosions.