I did the same when I was young, 13amp coiled mains extension lead running a high power space heater. I had some things I needed heating up prior to working on them. Left it running in the garage and all the lights went out. The coil was to hot to handle.
In those days the outer coating of the lead was often rubber or some rubber related item and it had heated up a lot. Whilst the problem was fixed the smell of molten rubber hung around for a long time. I was lucky not to have a fire! I can barely remember the days of youth and daft in equal parts.
