I found a few examples at ALC, but still not sure about the best way to say it.
- Anybody can ask a question
- Anybody can answer
- The best answers are voted up and rise to the top
For example, the most natural way of translating this expression
can be rephrased simply as follows:
Basically it is a fancier way of saying ～ことをまったく知らなかった where ～ is the statement that follows the expression.
I find the most natural way of translating this is to write 彼女は（息子が怒り出す）とは思わなかった, to show that the person was kind of caught off guard by what happened.