Exercise caution when microwaving eggs ... the results could be explosive

— -- It’s no yolk ... microwaving boiled eggs is a bad idea.

In fact, they may explode -– and superheated water may be the culprit, said researchers authoring a new report under an unusual set of circumstances.

Anthony Nash, in a presentation Wednesday at the Acoustical Society of America meeting in New Orleans, offered a possible explanation of how this YouTube-cherished phenomenon happens.

As a researcher for the acoustics consulting firm Charles M. Salter Associates, Nash was asked to serve as an expert witness for a case in which a shelled hard-boiled egg that was reheated in a microwave exploded in a restaurant patron’s mouth, causing burns and possibly hearing damage.

While many may assume that pressure buildup within the egg causes these explosions, even eggs that have their shells removed can explode. And, as the researchers point out, boiled egg whites are just too soft to hold the amount of pressure required.

Using the conditions laid out in the legal case as a guide, the researchers reheated nearly 100 eggs in a microwave. Two out of three ruptured during reheating. But for the third that made it out whole –- explosive results. When the researchers poked the eggs with an instant-read thermometer, they popped violently.

Turns out, microwaved yolks are, on average, 22 degrees Fahrenheit hotter than microwaved water –- in other words, yolk is more responsive to microwave heating that water is.

They theorize that pockets of water in the yolk get superheated. Superheated water doesn’t boil immediately because surface tension of the water prevents bubbles from forming. But once that surface tension is broken, like when these pockets are disturbed, they suddenly boil, releasing a lot of bubbles rapidly and violently and causing what appears to be an explosion.

The researchers also found that the loudest sound from an exploding egg a foot away is about 130 decibels, similar to a soft balloon pop, and unlikely to cause hearing damage.

As for what happened to the litigation: “They settled,” Nash said. “As a case, hearing damage was up in the air, but getting burned was 100 percent.”