Concatenate multiple row values if they have the same value in one column

I have a large spreadsheet that is sorted on repeating values in column C. Each row has a unique comment in column H that I would like to concatenate for each repeating value in column C. For example the 4 entries in column C that are the same should have their comments concatenated into a single cell along with a line break after each entry.

Does anyone have any ideas on how to do this?