I would just take off the black parts with a pair of sharp clean pruners. You are probably right about the too much water. I think the problem is that you may have roots rotting.
I would never put a bougainvillea in a mix with water crystals added because they would rather be bone dry than sit in water. I would go ahead and repot it now.
Use some good potting mix (2parts), 1 part sand, and 1 part perlite. You can use some vit B or superthrive diluted in water after repotting but do not fertilize for awhile.
I live in a super dry zone 10 and I have about 10 in pots now. This is the mix I use. I would rather pot up a size if they are wilting too much than use a richer soil, because they can rot easily due to thier fine roots.
They do live and flower very nicely in wet climates as well, but they must have excellent drainage. Hope this helps.
~SJN

Definitely sounds like it's excessive moisture. I purposely grow plants such as bougainvillea (also the palms) in smallish pots because my area is prone to periodic summer monsoons. When this has happened to me, I have hauled some of the more wet intolerant plants into the garage or house in order to dry out some and wait out the rain. Cut out anything rotting, let it dry out, pray for sun and drier air and I bet it will recuperate for you.

So...should I replant mine in a bowl type planter? Mine is growing like crazy, just not flowering. Some of the leaves are turing red, but this has been happening for a few months. This plant is outside in full sun and will come in in the winter.

Thanks so much for the responses and directions/advice! I will take care of it this evening......rain has slowed down considerably....wonder if this means we are about to start our drought season? Texas.....the land of extremes!

I tried a cutting recently and the symptoms are the same, the cutting started turning black on the end leaves.

My take on this is poor nutrients. A cutting's problem is that it has no roots yet. Your plant's problem is that it isn't getting food. Add some mulch and something to help break it down. If in pots, put in a bigger, deeper pot.

I would like to get a bougainvilla the next time I go to S.C. but I am wondering how big they get? Also, it was quite a shock to discover they have thorns! Do those of you who bring yours inside for the winter have any problem w/ the thorns?
SJN- thanks for the info on the right mix of soil to use. I definitely have plenty of sand here. Brandy

Brandy - I have bougainvillea growing in a built-in planter in my pool greenhouse, and they are absolutely huge. At least 15 feet tall, maybe more - they are climbing up some chicken wire we installed and go up the wall and partially across the top of the greenhouse.

That being said, we also have them in pots at our other place in southern Mexico. The guy that takes care of them regularly cuts them back quite a bit so they are more shrub-like in the pots, and they do well like that.

Well, I am also a cactus lover, but can honestly say that I haven't even noticed the thorns on the bougainvillea. Will go out tomorrow to check if they have them. As far as I'm concerned common holly is far worse for thorns. Buy your bougainvillea and don't worry about any thorns!