Yes and yes.
My first was spontaneous in nature and took place when I was in my preteens. I used to work on weekends and during the summer with my step-father, who was a plastering contractor in Chicago. We lived about 60 or so miles northwest of the city in a little town called Woodstock, so the commute took around an hour and a half with the morning stop at the material yard.
One morning, I was staring out the window of the truck at the buildings, the traffic, the people, the El (the elevated/subway train system that runs through the city) when out of nowhere I felt a sense of familiarity and intimacy with all of it...everything...as familiar as my living room or the back of my hand...like it was a part of me. I don't recall, even at the time, how long this lasted...probably just a few seconds...but the gravity of the experience made an impression on me that I would never forget, even though for years I wrote it off as some sort of an anomaly.
It wasn't until many years passed that I was talking to someone about the experience, and they suggested that it might be what they referred to as a spontaneous mystical experience. It was at that time which began to investigate, research, talk, contemplate, and meditate on the experience. I learned more about it, and it was able to find validation in Hindu scripture that verified with me that it was not just an anomaly. It pointed to what I am in my true nature.