How to make an explanation box as a pop-up?

I want to make my texts as accessible as possible, also for people with learning difficulties.
I write a text that sometimes contains a difficult word (for some readers).
A word that needs explanation.
What I would like to do, is that you can go over a difficult word with your mouse, and then a pop-up box pops up with an explanation of the difficult word or phrase.
See this example (in Dutch):

First:


Marked in blue are 'difficult words'.

Going over a blue word with the mouse results in:




As you can see, a box appears that contains an explanation or description of the difficult word.

How can I create this in Divi?