Student or Learner
I would like know the meaning of the next sentence.
He has all the patience of a boiling tea kettle.
He is not patient at all. He is - to use a not very common word, that all the same is not dated - 'seething'. 'Seething' - in today's use - means 'very angry', but once (until before the turn of the 19th century, I would guess) it meant 'simmering' (that is, what very hot stuff does just before it boils).
(I don't know whether the person who wrote your sentence knew that, but I find it interesting.)