School me on testing coils!

That breaking of the ground path has to happen very fast for the field to collapse and cause a spark. Its very likely that there is some making an breaking of the contact as you pull the wire from ground. If you were to have a scope on it there still would be a voltage but not enough to create a spark.

You should be checking the coil with an ohm meter. The primary will be very low, just 1 or 2 ohms and the secondary will be up in the range of 1000's of ohms.