It takes a certain skill and a good cooking sense to boil the perfect egg. There are many preferences and different tastes, but you can easily get it wrong the first few times.
Sometimes, the egg can end up being too dry or the yolk can separate itself from the white part.
This usually happens since eggs need two temperatures to cook both the yolk and the white. The egg white needs temperature of 180 degrees in order to be cooked perfectly, whereas the yolk requires 170 degrees.
One chef discovered the secret to a perfectly boiled egg and now he is sharing it with the world. What he did was, he put several eggs in pre-boiled water for 30 seconds and then added several ice cubes in order to diminish the heat.
Then he started pulling eggs out on two minutes difference. Here is how you can learn to cook the ideal egg, as demonstrated on the chart below.
Sources and References: