Bottled lager

hello all, new poster/homebrewer here.

I brewed a mexican cerveza for my first attempt, after about 4 weeks after bottling, it was excellent, held it's head all the way down the glass and was crystal clear (as long as it was carefully decanted out of the bottle)

Next batch was a german pilsner. I seem to be having a bit of a problem with this, brewed as per instructions, then bottled with half tespoon of brewers sugar and capped. Left for 4 weeks, opened one bottle, and it basically turned to froth all over the sink and didn't taste the best. I left the bottles for another 6 weeks, just opened another bottle, and it's done the same, out of a 750ml bottle, I can just about manage to get 1/2 pint of lager out of it, the rest is a very active froth that ends up in the sink. It doesn't taste the best, and looks even worse. The looks I'm putting down to the fact that with the explosion of bubbles, it's disturbing the sediment, but the non-lager taste it's got is causing a problem, still tastes quite yeasty

Is this just a case of leaving it for longer in the bottle?

cheers for any advice
Trev

It sounds like it might be an infection.

Sometimes if you use dry sugar that you haven't boiled, critters can live in the sugar. They can't reproduce (because they need an aqueous environment) but they can hide out until they are in your yummy, yummy beer.

Unfortunately: "gusher" bottles + bad taste = infection, most of the time. Sorry!

In the future, dissolve your sugar in water, boil that, and either batch prime (add your sterile syrup to the whole batch before bottling) or use a sanitized funnel to put a bit of liquid in each bottle.