More often than not, I am always telling people what their dogs are about to do just seconds before they do it. Some people think it's magic, others think it's luck, but the truth is, it's simply knowing and understanding Canine Communication.
I always try to teach people precursors to behaviours by highlighting body language. Body language is especially important to take note of if you're training your dog, or are working with a dog who has sensitivities. Knowing body indicators just might make the difference between having your dog involved in a scuffle, or in being able to prevent unfavourable behaviour. If you learn this stuff, you will be able to successfully redirect your dog's focus and have a more positive training outcome.
Here's a nice link with pictures that may help you identify what your dog is thinking, feeling, and what his/her next move might be as a result of what markers they're displaying. Hope it helps.