Foreshadowing, hint-dropping, a little tease here and there -- these are time-honored literary techniques that keep the reader hooked and wanting more. But you can get to a point where you've just pushed the reader too far. If you tease, and tease, and tease, even when you deliver you won't get the reaction you wanted.
Looking Into the Future
Foreshadowing is a fancy literary term for hint-dropping. When you allude to the reader that something is about to happen, or if you say so outright (which is generally what I do in my writing), you're foreshadowing. You are, essentially, dropping teasers about upcoming chapters of the book. And like any good literary technique, it can be over-done.
In other words, you can't drop too many hints. I read a book, once, with a main character had a very extensive backstory. Now, this is not unusual. The fact that the author teased this backstory, without revealing it, and for a good 80 percent of the book, was unusual. And frankly, I no longer cared about the backstory when it was revealed in very anticlimactic fashion.
Ever pulled on a dryer sheet? It's resilient up to a point. You can pull it, and stretch it, but only so far. Keep pulling, and it will rip in two. The patience of your readers is a dryer sheet. You can pull and stretch, but only a little. Take it too far, and their patience is going to snap. They're going to stop caring, and that's not where you want your readers to be.
Tease once, and you're building anticipation. Tease twice, and you're drawing out the suspense. Keep doing it, and you're playing with fire. Like all literary techniques, foreshadowing should be used in moderation. When writing, please remember to tease responsibly.