al dente, a touch of salt, maybe a dash of denatured yak bile...
My bass teacher when I was first learning was a French man with a very thick French accent. When I told him that I had tried boiling my strings to make them last longer he remarked "oh, deux you alseau add some rosemaree and oleeve oyel?"
I haven't done it in a while but I recall it helping for a bit, however it didn't add a ton of life and it seems like more hassle than it's worth for me now.