I just started fishing carp this summer. As with much of my other fishing, it was a total failure.
One thing I noticed is that my store bought boilies would come out of the water after 15 minutes to an hour looking just like they went in. Am I mistaken that boilies should slowly dissolve?
Some boilies dissolve better/faster than others, that depends on how they were made. Can you crush them by hand? if yes then the boiles are fine. If you cant you may want to change boilies!
Try using corn (flavored corn or store bought) and chum chum chum! I throw out about 3 corns of sweetcorn while I fish (I throw out a quarter of a cup every 15-20 minutes)