Praktisch gezien: heb ik geen kookthermometer
Maar ik let wel hier op:
Contrary to the notion that "a watched pot never boils," as water’s temperature increases, it goes through several major, visually recognizable stages. These stages have been recognized and used in China since ancient times. Since it has been around so long, there is regional and chronological variance in the naming and in the corresponding temperature ranges for each name, but generally speaking the guidelines are as follows:
Shrimp Eyes: (70-80deg C)
This stage is marked by the appearance of tiny bubbles on the edges and bottom of the pot. They are, obviously, the size of shrimp eyes. (For those of you who haven’t looked a crustacean in the eyes lately, it’s under 3mm.) These bubbles are not from the breaking of the chemical bonds in the water itself, but from the escape of the dissolved gases in it.
Crab Eyes: (80-90deg C)
The transition from shrimp eyes to crab eyes occurs when the tiny bubbles begin to rise. It will have a gentle steam rising from it and it makes rapid, high-pitched sizzling sounds with the rise of the bubbles, which are around 3mm in size. This stage was also referred to as the "first boiling."
Fish Eyes: (90-95deg C)
Just like the name says, the bubbles are larger than crab eyes (around 8mm). There is much more steam, and the steam will rise faster than it did in the crab eyes stage. The sound of the hiss will lower in pitch. This stage is also called the "second boiling."
Dragon Eyes: (100deg C)
This stage is commonly referred to as a "full boil" or "rolling boil," and less commonly as "Old Man Water" or the "third boiling." It is marked by the absence of any small bubbles (as the dissolved gases have all escaped) and the presence of large bubbles (the size of dragon eyes, right?) formed by the evaporation of the water itself.