I made two batches today, because a friend gave me an empty container. =)
As usual, as soon as I added the Washing Soda, the mild simmer turned into a raging boil (Great band name, the "Raging Boils". Wait, maybe not.) and boiled over all over. Blech. The laundry detergent has a pretty thick consistency, so cleaning it up was nauseating.
Second batch. I managed to skip the messy over boiling this time, but...
I let it cool a little too long before putting it in the bottles. Mmm! Chunk of soap, anyone?
Warmed it up again and stirred. Managed to bottle it. Whew!