What appear as coincidences are not coincidences - only our limited mind cannot see the causal connection. It is said that if a butterfly flutters its wings in China, it leads to Tsunami in a distant land. In other words, no event or phenomena is beyond the scope of causal connection. Now at the spiritual level, you're probably referring to strange coincidences like you are suddenly reminded of a person long forgotten and he comes to meet you beyond expectations or things of similar nature. Phenomena of similar nature or psychic phenomena of deeply strange/mysterious nature have been scientifically studied by the Institute of Psychical Research for more than 100 years. And their conclusion is that psychic events are real. Coincidences are meaningful and there are entities beyond our senses that participate/intervene in our lives.