Unexpected Sequels to Novels

I keep starting to read novels only to find out that the story is uncompleted at the end and continued in a sequel (or sequels).  Often that sequel is not even published yet!  This is extremely irritating and I find it unacceptable that this information is not readily available on Amazon where I buy or borrow the book.  Often you can find this out by looking through the customer reviews on Amazon, but that's not ideal since there's a propensity for some people to give spoilers. And by the time the sequel has been published I've read a huge number of other books in between and I can't remember the story!